The national study found that a majority of Medicaid patients younger than 65 visit emergency rooms for serious medical problems that call for urgent care. That finding runs counter to prevailing beliefs about how those on the state- and federally-funded insurance program seek medical attention.

But the study also found that Medicaid patients under the age of 65 use emergency rooms twice as often as those of the same age who have private insurance.

Researchers say that’s because those on Medicaid are typically sicker than privately insured adults. The study found the same patterns among teens and young adults aged 13 to 20.

Injuries comprised the largest share of ER visits by 21- to 64-year-olds on Medicaid, and those patients sought treatment for injuries at double the rate of those on private insurance.

Researchers say such information can help policymakers develop more efficient and lower-cost settings for the treatment of medical problems most common to those on Medicaid.

Correction: The headline for this story initially said "Medicare" instad of "Medicaid."